Remember last spring when I posted a picture of a small tree and we decided it was a mimosa tree? We discovered yesterday that it was blooming. It is about six feet tall now but not very big around. Here are a couple of pictures of the flowers. A few more flowers ( photo / image / picture from dooley's Garden ) Yellow flowers on little tree ( photo / image / picture from dooley's Garden ) dooley
Yours is in the same family as the Albizia julibrissin (Mimosa Tree, Silk Tree, Pink Siris) but Mimosa flowers are pink. Yours looks more like Laburnum alpine or another species of the Genus Laburnum. It's also called Golden Chain. Because they are both in the Pea Family they will have similar leaves. Take a look at the third photo on the GS Albizia julibrissin page, the growth pattern of the tree appears to be very different from yours.
I agree with Toni... not a Mimosa.... although obviously related. So glad that it's a Golden Chain (which I had to look up online) and not that "weed tree" known as rattlebox.